Many of you know already that “Wicked” will sweep into town for a fourth visit to the Buell Theatre, beginning April 11 through May 20. The blockbuster musical recounts the backstory of onetime friends Elphaba and Glinda — the naughty and nice witches of a land called Oz.

What comes as delicious news is that while the play’s in town, its evidently tireless cast will be out front for one evening, strutting its stuff at the Ogden Theatre in an mashup worthy of “Glee”: “The Wicked Rocky Horror Show.”